Coverage contour and interference thresholds for channel assignment

ABSTRACT

Aspects of the present disclosure relate to methods and apparatus for improving coverage contour and interference thresholds for general authorized access (GAA) channel assignment in a wireless communications environment.

CLAIM OF PRIORITY UNDER 35 U.S.C. § 119

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 62/417,242, filed Nov. 3, 2016, which is herein incorporated byreference in its entirety as if fully set forth below and for allapplicable purposes.

FIELD OF THE DISCLOSURE

Certain aspects of the present disclosure generally relate to wirelesscommunications and, more particularly, to techniques for improvingcoverage contour and interference thresholds for general authorizedaccess (GAA) channel assignment.

DESCRIPTION OF RELATED ART

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, data, video, and the like,and deployments are likely to increase with introduction of new dataoriented systems such as Long Term Evolution (LTE) systems. Wirelesscommunication systems may be multiple-access systems capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., bandwidth and transmit power). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE)systems, and other orthogonal frequency division multiple access (OFDMA)systems.

Generally, a wireless multiple-access communication system cansimultaneously support communication for multiple wireless terminals(also known as user equipments (UEs), user terminals, or accessterminals (ATs)). Each terminal communicates with one or more basestations (also known as access points (APs), eNodeBs, or eNBs) viatransmissions on forward and reverse links. The forward link (alsoreferred to as a downlink or DL) refers to the communication link fromthe base stations to the terminals, and the reverse link (also referredto as an uplink or UL) refers to the communication link from theterminals to the base stations. These communication links may beestablished via single-in-single-out, single-in-multiple out,multiple-in-single-out, or multiple-in-multiple-out (MIMO) systems.

Newer multiple access systems, for example, LTE, deliver faster datathroughput than older technologies. Faster downlink rates, in turn, havesparked a greater demand for higher-bandwidth content, such ashigh-resolution graphics and video, for use on or with mobile devices.Therefore, demand for bandwidth on wireless communications systemscontinues to increase despite availability of higher data throughputover wireless interfaces, and this trend is likely to continue. However,wireless spectrum is a limited and regulated resource. Therefore, newapproaches are needed in wireless communications to more fully utilizethis limited resource and satisfy consumer demand.

SUMMARY

The systems, methods, and devices of the disclosure each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this disclosure as expressedby the claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “DETAILED DESCRIPTION” one will understand how thefeatures of this disclosure provide advantages that include improvedcommunications between access points and stations in a wireless network.

Certain aspects of the present disclosure generally relate to techniquesfor improving coverage contour and interference thresholds for generalauthorized access (GAA) channel assignment.

Certain aspects of the present disclosure provide a method of assigningchannels in a wireless communications environment. The method generallyincludes determining a coverage contour threshold and an interferencethreshold for each entity of a plurality of entities in the wirelesscommunications environment, deciding whether a first entity and a secondentity overlap in coverage based on the coverage contour threshold andthe interference threshold for the first entity and the second entity,wherein the first entity and the second entity overlap if interferencefrom the first entity is greater than the interference threshold for thesecond entity at any point at a boundary of or inside the coveragecontour threshold of the second entity, and selecting a channelassignment for the first entity and the second entity based on thedecision, wherein determining a channel assignment for the first entityand the second entity comprises assigning the first entity and thesecond entity orthogonal channels if the first entity and the secondentity overlap in coverage.

Certain aspects of the present disclosure provide an apparatus forassigning channels in a wireless communications environment. Theapparatus generally includes at least one processor configured todetermine a coverage contour threshold and an interference threshold foreach entity of a plurality of entities in the wireless communicationsenvironment, decide whether a first entity and a second entity overlapin coverage based on the coverage contour threshold and the interferencethreshold for the first entity and the second entity, wherein the firstentity and the second entity overlap if interference from the firstentity is greater than the interference threshold for the second entityat any point at a boundary of or inside the coverage contour thresholdof the second entity, and select a channel assignment for the firstentity and the second entity based on the decision, wherein selecting achannel assignment for the first entity and the second entity comprisesassigning the first entity and the second entity orthogonal channels ifthe first entity and the second entity overlap in coverage. Theapparatus also generally includes a memory coupled with the at least oneprocessor.

Certain aspects of the present disclosure provide an apparatus forassigning channels in a wireless communications environment. Theapparatus generally includes means for determining a coverage contourthreshold and an interference threshold for each entity of a pluralityof entities in the wireless communications environment, means fordeciding whether a first entity and a second entity overlap in coveragebased on the coverage contour threshold and the interference thresholdfor the first entity and the second entity, wherein the first entity andthe second entity overlap if interference from the first entity isgreater than the interference threshold for the second entity at anypoint at a boundary of or inside the coverage contour threshold of thesecond entity, and means for selecting a channel assignment for thefirst entity and the second entity based on the decision, whereinselecting a channel assignment for the first entity and the secondentity comprises assigning the first entity and the second entityorthogonal channels if the first entity and the second entity overlap incoverage.

Certain aspects of the present disclosure provide an apparatus forassigning channels in a wireless communications environment. Theapparatus generally includes instructions that, when executed by atleast one processor, configure the at least one processor to determine acoverage contour threshold and an interference threshold for each entityof a plurality of entities in the wireless communications environment,decide whether a first entity and a second entity overlap in coveragebased on the coverage contour threshold and the interference thresholdfor the first entity and the second entity, wherein the first entity andthe second entity overlap if interference from the first entity isgreater than the interference threshold for the second entity at anypoint at a boundary of or inside the coverage contour threshold of thesecond entity, and select a channel assignment for the first entity andthe second entity based on the decision, wherein selecting a channelassignment for the first entity and the second entity comprisesassigning the first entity and the second entity orthogonal channels ifthe first entity and the second entity overlap in coverage.

Numerous other aspects are provided including methods, apparatus,systems, computer program products, computer-readable medium, andprocessing systems. To the accomplishment of the foregoing and relatedends, the one or more aspects comprise the features hereinafter fullydescribed and particularly pointed out in the claims. The followingdescription and the annexed drawings set forth in detail certainillustrative features of the one or more aspects. These features areindicative, however, of but a few of the various ways in which theprinciples of various aspects may be employed, and this description isintended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the appended drawings. It is to be noted,however, that the appended drawings illustrate only certain typicalaspects of this disclosure and are therefore not to be consideredlimiting of its scope, for the description may admit to other equallyeffective aspects.

FIG. 1 is a diagram illustrating an example of a network architecture,in accordance with certain aspects of the disclosure.

FIG. 2 is a diagram illustrating an example of an access network, inaccordance with certain aspects of the disclosure.

FIG. 3 is a diagram illustrating an example of a DL frame structure inLTE, in accordance with certain aspects of the disclosure.

FIG. 4 is a diagram illustrating an example of an UL frame structure inLTE, in accordance with certain aspects of the disclosure.

FIG. 5 is a diagram illustrating an example of a radio protocolarchitecture for the user and control plane, in accordance with certainaspects of the disclosure.

FIG. 6 is a diagram illustrating an example of an evolved Node B anduser equipment in an access network, in accordance with certain aspectsof the disclosure.

FIG. 7 is a block diagram showing aspects of an Authorized Shared Access(ASA) controller coupled to different wireless communication systemsincluding one primary user and one secondary user, in accordance withcertain aspects of the disclosure.

FIG. 8 is a block diagram showing aspects of an ASA controller coupledto different wireless communication systems including one primary userand multiple secondary users, in accordance with certain aspects of thedisclosure.

FIG. 9 illustrates an example architecture of a spectrum sharing system,in accordance with certain aspects of the disclosure.

FIG. 10 illustrates example operations for assigning channels to aplurality of networks in a wireless communications environment, inaccordance with certain aspects of the present disclosure.

FIG. 11 shows a communication device illustrating means for performingoperations for assigning channels, according to certain aspects of thepresent disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in one aspectmay be beneficially utilized on other aspects without specificrecitation.

DETAILED DESCRIPTION

Aspects of the present disclosure provide techniques for assigningchannels to networks (e.g., network operators) co-existing in the samespectrum, for example, a 3.5 GHz spectrum, and that may be subject tointerference limitations with respect to other networks in the samespectrum. For example, aspects of the present disclosure providetechniques for improving coverage contour and interference thresholdsfor general authorized access (GAA) channel assignment (e.g., within the3.5 GHz spectrum). As will be explained in greater detail below, in somecases, these coverage and interference thresholds may be determined as afunction of interference and throughput of an assigned channelbandwidth.

The techniques described herein may be used for various wirelesscommunication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA andother networks. The terms “network” and “system” are often usedinterchangeably. A CDMA network may implement a radio technology such asuniversal terrestrial radio access (UTRA), cdma2000, etc. UTRA includeswideband CDMA (WCDMA), time division synchronous CDMA (TD-SCDMA), andother variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856standards. A TDMA network may implement a radio technology such asglobal system for mobile communications (GSM). An OFDMA network mayimplement a radio technology such as evolved UTRA (E-UTRA), ultra mobilebroadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20,Flash-OFDM®, etc. UTRA and E-UTRA are part of universal mobiletelecommunication system (UMTS). 3GPP Long Term Evolution (LTE) andLTE-Advanced (LTE-A), in both frequency division duplex (FDD) and timedivision duplex (TDD), are new releases of UMTS that use E-UTRA, whichemploys OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA,UMTS, LTE, LTE-A and GSM are described in documents from an organizationnamed “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB aredescribed in documents from an organization named “3rd GenerationPartnership Project 2” (3GPP2). The techniques described herein may beused for the wireless networks and radio technologies mentioned above aswell as other wireless networks and radio technologies. For clarity,certain aspects of the techniques are described below forLTE/LTE-Advanced, and LTE/LTE-Advanced terminology is used in much ofthe description below. LTE and LTE-A are referred to generally as LTE.

A wireless communication network may include a number of base stationsthat can support communication for a number of wireless devices.Wireless devices may include user equipments (UEs). Some examples of UEsmay include cellular phones, smart phones, personal digital assistants(PDAs), wireless modems, handheld devices, tablets, laptop computers,netbooks, smartbooks, ultrabooks, wearables (e.g., smart watch, smartbracelet, smart glasses, smart ring, smart clothing), etc.

System designs may support various time-frequency reference signals forthe downlink and uplink to facilitate beamforming and other functions. Areference signal is a signal generated based on known data and may alsobe referred to as a pilot, preamble, training signal, sounding signal,and the like. A reference signal may be used by a receiver for variouspurposes such as channel estimation, coherent demodulation, channelquality measurement, signal strength measurement, and the like. MIMOsystems using multiple antennas generally provide for coordination ofsending of reference signals between antennas; however, LTE systems donot in general provide for coordination of sending of reference signalsfrom multiple base stations or eNBs.

In some implementations, a system may use time division duplexing (TDD).For TDD, the downlink and uplink share the same frequency spectrum orchannel, and downlink and uplink transmissions are sent on the samefrequency spectrum. The downlink channel response may thus be correlatedwith the uplink channel response. Reciprocity may allow a downlinkchannel to be estimated based on transmissions sent via the uplink.These uplink transmissions may be reference signals or uplink controlchannels (which may be used as reference symbols after demodulation).The uplink transmissions may allow for estimation of a space-selectivechannel via multiple antennas.

In LTE implementations, orthogonal frequency division multiplexing(OFDM) is used for the downlink—that is, from a base station, accesspoint or eNodeB (eNB) to a user terminal or UE. Use of OFDM meets theLTE requirement for spectrum flexibility and enables cost-efficientsolutions for very wide carriers with high peak rates, and is awell-established technology. For example, OFDM is used in standards suchas IEEE 802.11a/g, 802.16, High Performance Radio LAN-2 (HIPERLAN-2,wherein LAN stands for Local Area Network) standardized by the EuropeanTelecommunications Standards Institute (ETSI), Digital VideoBroadcasting (DVB) published by the Joint Technical Committee of ETSI,and other standards.

Time frequency physical resource blocks (also denoted here in asresource blocks or “RBs” for brevity) may be defined in OFDM systems asgroups of transport carriers (e.g., sub-carriers) or intervals that areassigned to transport data. The RBs are defined over a time andfrequency period. Resource blocks are comprised of time-frequencyresource elements (also denoted here in as resource elements or “REs”for brevity), which may be defined by indices of time and frequency in aslot. Additional details of LTE RBs and REs are described in the 3GPPspecifications, such as, for example, 3GPP TS 36.211.

UMTS LTE supports scalable carrier bandwidths from 20 MHz down to 1.4MHZ. In LTE, an RB is defined as 12 sub-carriers when the subcarrierbandwidth is 15 kHz, or 24 sub-carriers when the sub-carrier bandwidthis 7.5 kHz. In an exemplary implementation, in the time domain there isa defined radio frame that is 10 ms long and consists of 10 subframes of1 millisecond (ms) each. Every subframe consists of 2 slots, where eachslot is 0.5 ms. The subcarrier spacing in the frequency domain in thiscase is 15 kHz. Twelve of these subcarriers together (per slot)constitute an RB, so in this implementation one resource block is 180kHz. Six Resource blocks fit in a carrier of 1.4 MHz and 100 resourceblocks fit in a carrier of 20 MHz.

Various other aspects and features of the disclosure are furtherdescribed below. It should be apparent that the teachings herein may beembodied in a wide variety of forms and that any specific structure,function, or both being disclosed herein is merely representative andnot limiting. Based on the teachings herein one of an ordinary level ofskill in the art should appreciate that an aspect disclosed herein maybe implemented independently of any other aspects and that two or moreof these aspects may be combined in various ways. For example, anapparatus may be implemented or a method may be practiced using anynumber of the aspects set forth herein. In addition, such an apparatusmay be implemented or such a method may be practiced using otherstructure, functionality, or structure and functionality in addition toor other than one or more of the aspects set forth herein. For example,a method may be implemented as part of a system, device, apparatus,and/or as instructions stored on a computer-readable medium forexecution on a processor or computer. Furthermore, an aspect maycomprise at least one element of a claim.

It is noted that while aspects may be described herein using terminologycommonly associated with 3G and/or 4G wireless technologies, aspects ofthe present disclosure can be applied in other generation-basedcommunication systems, such as 5G and later.

An Example Wireless Communications System

FIG. 1 is a diagram illustrating an LTE network architecture 100 inwhich aspects of the present disclosure may be practiced. For example, acore network entity (not shown) may determine coverage contour andinterference thresholds for networks operating in a wirelesscommunications environment so as to optimally reduce interference seenin these networks while maintaining an acceptable channel throughput(e.g., bandwidth).

The LTE network architecture 100 may be referred to as an Evolved PacketSystem (EPS) 100. The EPS 100 may include one or more user equipment(UE) 102, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN)104, an Evolved Packet Core (EPC) 110, a Home Subscriber Server (HSS)120, and an Operator's IP Services 122. The EPS can interconnect withother access networks, but for simplicity those entities/interfaces arenot shown. Exemplary other access networks may include an IP MultimediaSubsystem (IMS) PDN, Internet PDN, Administrative PDN (e.g.,Provisioning PDN), carrier-specific PDN, operator-specific PDN, and/orGPS PDN. As shown, the EPS provides packet-switched services, however,as those skilled in the art will readily appreciate, the variousconcepts presented throughout this disclosure may be extended tonetworks providing circuit-switched services.

The E-UTRAN includes the evolved Node B (eNB) 106 and other eNBs 108.The eNB 106 provides user and control plane protocol terminations towardthe UE 102. The eNB 106 may be connected to the other eNBs 108 via an X2interface (e.g., backhaul). The eNB 106 may also be referred to as abase station, a base transceiver station, a radio base station, a radiotransceiver, a transceiver function, a basic service set (BSS), anextended service set (ESS), an access point, or some other suitableterminology. The eNB 106 may provide an access point to the EPC 110 fora UE 102. Examples of UEs 102 include a cellular phone, a smart phone, asession initiation protocol (SIP) phone, a laptop, a personal digitalassistant (PDA), a satellite radio, a global positioning system, amultimedia device, a video device, a digital audio player (e.g., MP3player), a camera, a game console, a tablet, a netbook, a smart book, anultrabook, a drone, a robot, a sensor, a monitor, a meter, or any othersimilar functioning device. The UE 102 may also be referred to by thoseskilled in the art as a mobile station, a subscriber station, a mobileunit, a subscriber unit, a wireless unit, a remote unit, a mobiledevice, a wireless device, a wireless communications device, a remotedevice, a mobile subscriber station, an access terminal, a mobileterminal, a wireless terminal, a remote terminal, a handset, a useragent, a mobile client, a client, or some other suitable terminology.

The eNB 106 is connected by an 51 interface to the EPC 110. The EPC 110includes a Mobility Management Entity (MME) 112, other MMEs 114, aServing Gateway 116, and a Packet Data Network (PDN) Gateway 118. TheMME 112 is the control node that processes the signaling between the UE102 and the EPC 110. Generally, the MME 112 provides bearer andconnection management. All user IP packets are transferred through theServing Gateway 116, which itself is connected to the PDN Gateway 118.The PDN Gateway 118 provides UE IP address allocation as well as otherfunctions. The PDN Gateway 118 is connected to the Operator's IPServices 122. The Operator's IP Services 122 may include, for example,the Internet, the Intranet, an IP Multimedia Subsystem (IMS), and a PS(packet-switched) Streaming Service (PSS). In this manner, the UE102 maybe coupled to the PDN through the LTE network.

FIG. 2 is a diagram illustrating an example of an access network 200 inan LTE network architecture in which aspects of the present disclosuremay be practiced. For example, a core network entity (not shown) maydetermine coverage contour and interference thresholds for the accessnetwork 200 operating in a wireless communications environment so as tooptimally reduce interference seen in the access network 200 (e.g.,caused by other networks in the wireless communications environment)while maintaining an acceptable channel throughput (e.g., bandwidth) forthe access network 200.

In this example, the access network 200 is divided into a number ofcellular regions (cells) 202. One or more lower power class eNBs 208 mayhave cellular regions 210 that overlap with one or more of the cells202. A lower power class eNB 208 may be referred to as a remote radiohead (RRH). The lower power class eNB 208 may be a femto cell (e.g.,home eNB (HeNB)), pico cell, or micro cell. The macro eNBs 204 are eachassigned to a respective cell 202 and are configured to provide anaccess point to the EPC 110 for all the UEs 206 in the cells 202. Thereis no centralized controller in this example of an access network 200,but a centralized controller may be used in alternative configurations.The eNBs 204 are responsible for all radio related functions includingradio bearer control, admission control, mobility control, scheduling,security, and connectivity to the serving gateway 116. The network 200may also include one or more relays (not shown). According to oneapplication, a UE may serve as a relay.

The modulation and multiple access scheme employed by the access network200 may vary depending on the particular telecommunications standardbeing deployed. In LTE applications, OFDM is used on the DL and SC-FDMAis used on the UL to support both frequency division duplexing (FDD) andtime division duplexing (TDD). As those skilled in the art will readilyappreciate from the detailed description to follow, the various conceptspresented herein are well suited for LTE applications. However, theseconcepts may be readily extended to other telecommunication standardsemploying other modulation and multiple access techniques. By way ofexample, these concepts may be extended to Evolution-Data Optimized(EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interfacestandards promulgated by the 3rd Generation Partnership Project 2(3GPP2) as part of the CDMA2000 family of standards and employs CDMA toprovide broadband Internet access to mobile stations. These concepts mayalso be extended to Universal Terrestrial Radio Access (UTRA) employingWideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA;Global System for Mobile Communications (GSM) employing TDMA; andEvolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employingOFDMA. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents fromthe 3GPP organization. CDMA2000 and UMB are described in documents fromthe 3GPP2 organization. The actual wireless communication standard andthe multiple access technology employed will depend on the specificapplication and the overall design constraints imposed on the system.

The eNBs 204 may have multiple antennas supporting MIMO technology. Theuse of MIMO technology enables the eNBs 204 to exploit the spatialdomain to support spatial multiplexing, beamforming, and transmitdiversity. Spatial multiplexing may be used to transmit differentstreams of data simultaneously on the same frequency. The data streamsmay be transmitted to a single UE 206 to increase the data rate or tomultiple UEs 206 to increase the overall system capacity. This isachieved by spatially precoding each data stream (e.g., applying ascaling of an amplitude and a phase) and then transmitting eachspatially precoded stream through multiple transmit antennas on the DL.The spatially precoded data streams arrive at the UE(s) 206 withdifferent spatial signatures, which enables each of the UE(s) 206 torecover the one or more data streams destined for that UE 206. On theUL, each UE 206 transmits a spatially precoded data stream, whichenables the eNB 204 to identify the source of each spatially precodeddata stream.

Spatial multiplexing is generally used when channel conditions are good.When channel conditions are less favorable, beamforming may be used tofocus the transmission energy in one or more directions. This may beachieved by spatially precoding the data for transmission throughmultiple antennas. To achieve good coverage at the edges of the cell, asingle stream beamforming transmission may be used in combination withtransmit diversity.

In the detailed description that follows, various aspects of an accessnetwork will be described with reference to a MIMO system supportingOFDM on the DL. OFDM is a spread-spectrum technique that modulates dataover a number of subcarriers within an OFDM symbol. The subcarriers arespaced apart at precise frequencies. The spacing provides“orthogonality” that enables a receiver to recover the data from thesubcarriers. In the time domain, a guard interval (e.g., cyclic prefix)may be added to each OFDM symbol to combat inter-OFDM-symbolinterference. The UL may use SC-FDMA in the form of a DFT-spread OFDMsignal to compensate for high peak-to-average power ratio (PAPR).

FIG. 3 is a diagram 300 illustrating an example of a DL frame structurein LTE. A frame (10 ms) may be divided into 10 equally sized sub-frameswith indices of 0 through 9. Each sub-frame may include two consecutivetime slots. A resource grid may be used to represent two time slots,each time slot including a resource block. The resource grid is dividedinto multiple resource elements. In LTE, a resource block contains 12consecutive subcarriers in the frequency domain and, for a normal cyclicprefix in each OFDM symbol, 7 consecutive OFDM symbols in the timedomain, or 84 resource elements. For an extended cyclic prefix, aresource block contains 6 consecutive OFDM symbols in the time domainand has 72 resource elements. Some of the resource elements, asindicated as R 302, R 304, include DL reference signals (DL-RS). TheDL-RS include Cell-specific RS (CRS) (also sometimes called common RS)302 and UE-specific RS (UE-RS) 304. UE-RS 304 are transmitted only onthe resource blocks upon which the corresponding physical DL sharedchannel (PDSCH) is mapped. The number of bits carried by each resourceelement depends on the modulation scheme. Thus, the more resource blocksthat a UE receives and the higher the modulation scheme, the higher thedata rate for the UE.

In LTE, an eNB may send a primary synchronization signal (PSS) and asecondary synchronization signal (SSS) for each cell in the eNB. Theprimary and secondary synchronization signals may be sent in symbolperiods 6 and 5, respectively, in each of subframes 0 and 5 of eachradio frame with the normal cyclic prefix (CP). The synchronizationsignals may be used by UEs for cell detection and acquisition. The eNBmay send a Physical Broadcast Channel (PBCH) in symbol periods 0 to 3 inslot 1 of subframe 0. The PBCH may carry certain system information.

The eNB may send a Physical Control Format Indicator Channel (PCFICH) inthe first symbol period of each subframe. The PCFICH may convey thenumber of symbol periods (M) used for control channels, where M may beequal to 1, 2 or 3 and may change from subframe to subframe. M may alsobe equal to 4 for a small system bandwidth, e.g., with less than 10resource blocks. The eNB may send a Physical HARQ Indicator Channel(PHICH) and a Physical Downlink Control Channel (PDCCH) in the first Msymbol periods of each subframe. The PHICH may carry information tosupport hybrid automatic repeat request (HARQ). The PDCCH may carryinformation on resource allocation for UEs and control information fordownlink channels. The eNB may send a Physical Downlink Shared Channel(PDSCH) in the remaining symbol periods of each subframe. The PDSCH maycarry data for UEs scheduled for data transmission on the downlink.

The eNB may send the PSS, SSS, and PBCH in the center 1.08 MHz of thesystem bandwidth used by the eNB. The eNB may send the PCFICH and PHICHacross the entire system bandwidth in each symbol period in which thesechannels are sent. The eNB may send the PDCCH to groups of UEs incertain portions of the system bandwidth. The eNB may send the PDSCH tospecific UEs in specific portions of the system bandwidth. The eNB maysend the PSS, SSS, PBCH, PCFICH, and PHICH in a broadcast manner to allUEs, may send the PDCCH in a unicast manner to specific UEs, and mayalso send the PDSCH in a unicast manner to specific UEs.

A number of resource elements may be available in each symbol period.Each resource element (RE) may cover one subcarrier in one symbol periodand may be used to send one modulation symbol, which may be a real orcomplex value. Resource elements not used for a reference signal in eachsymbol period may be arranged into resource element groups (REGs). EachREG may include four resource elements in one symbol period. The PCFICHmay occupy four REGs, which may be spaced approximately equally acrossfrequency, in symbol period 0. The PHICH may occupy three REGs, whichmay be spread across frequency, in one or more configurable symbolperiods. For example, the three REGs for the PHICH may all belong insymbol period 0 or may be spread in symbol periods 0, 1, and 2. ThePDCCH may occupy 9, 18, 36, or 72 REGs, which may be selected from theavailable REGs, in the first M symbol periods, for example. Only certaincombinations of REGs may be allowed for the PDCCH. In aspects of thepresent methods and apparatus, a subframe may include more than onePDCCH.

A UE may know the specific REGs used for the PHICH and the PCFICH. TheUE may search different combinations of REGs for the PDCCH. The numberof combinations to search is typically less than the number of allowedcombinations for the PDCCH. An eNB may send the PDCCH to the UE in anyof the combinations that the UE will search.

FIG. 4 is a diagram 400 illustrating an example of an UL frame structurein LTE. The available resource blocks for the UL may be partitioned intoa data section and a control section. The control section may be formedat the two edges of the system bandwidth and may have a configurablesize. The resource blocks in the control section may be assigned to UEsfor transmission of control information. The data section may includeall resource blocks not included in the control section. The UL framestructure results in the data section including contiguous subcarriers,which may allow a single UE to be assigned all of the contiguoussubcarriers in the data section.

A UE may be assigned resource blocks 410 a, 410 b in the control sectionto transmit control information to an eNB. The UE may also be assignedresource blocks 420 a, 420 b in the data section to transmit data to theeNB. The UE may transmit control information in a physical UL controlchannel (PUCCH) on the assigned resource blocks in the control section.The UE may transmit only data or both data and control information in aphysical UL shared channel (PUSCH) on the assigned resource blocks inthe data section. A UL transmission may span both slots of a subframeand may hop across frequency.

A set of resource blocks may be used to perform initial system accessand achieve UL synchronization in a physical random access channel(PRACH) 430. The PRACH 430 carries a random sequence and cannot carryany UL data/signaling. Each random access preamble occupies a bandwidthcorresponding to six consecutive resource blocks. The starting frequencyis specified by the network. That is, the transmission of the randomaccess preamble is restricted to certain time and frequency resources.There is no frequency hopping for the PRACH. The PRACH attempt iscarried in a single subframe (1 ms) or in a sequence of few contiguoussubframes and a UE can make only a single PRACH attempt per frame (10ms).

FIG. 5 is a diagram 500 illustrating an example of a radio protocolarchitecture for the user and control planes in LTE. The radio protocolarchitecture for the UE and the eNB is shown with three layers: Layer 1,Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer andimplements various physical layer signal processing functions. The L1layer will be referred to herein as the physical layer 506. Layer 2 (L2layer) 508 is above the physical layer 506 and is responsible for thelink between the UE and eNB over the physical layer 506.

In the user plane, the L2 layer 508 includes a media access control(MAC) sublayer 510, a radio link control (RLC) sublayer 512, and apacket data convergence protocol (PDCP) 514 sublayer, which areterminated at the eNB on the network side. Although not shown, the UEmay have several upper layers above the L2 layer 508 including a networklayer (e.g., IP layer) that is terminated at the PDN gateway 118 on thenetwork side, and an application layer that is terminated at the otherend of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 514 provides multiplexing between different radiobearers and logical channels. The PDCP sublayer 514 also provides headercompression for upper layer data packets to reduce radio transmissionoverhead, security by ciphering the data packets, and handover supportfor UEs between eNBs. The RLC sublayer 512 provides segmentation andreassembly of upper layer data packets, retransmission of lost datapackets, and reordering of data packets to compensate for out-of-orderreception due to hybrid automatic repeat request (HARQ). The MACsublayer 510 provides multiplexing between logical and transportchannels. The MAC sublayer 510 is also responsible for allocating thevarious radio resources (e.g., resource blocks) in one cell among theUEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNBis substantially the same for the physical layer 506 and the L2 layer508 with the exception that there is no header compression function forthe control plane. The control plane also includes a radio resourcecontrol (RRC) sublayer 516 in Layer 3 (L3 layer). The RRC sublayer 516is responsible for obtaining radio resources (i.e., radio bearers) andfor configuring the lower layers using RRC signaling between the eNB andthe UE.

FIG. 6 is a block diagram of an eNB 610 in communication with a UE 650in an access network, in which aspects of the present disclosure may bepracticed. For example, a central entity (not shown) may evaluate anamount of transmission limitation imposed on each pair of channel andgroup of eNBs (e.g., eNBs 610) assigned to the respective channel. Thecentral entity may assign a channel to each group of eNBs based on theevaluation. It may be noted that the central entity may be implementedby eNB 610 or UE 650.

In the DL, upper layer packets from the core network are provided to acontroller/processor 675. The controller/processor 675 implements thefunctionality of the L2 layer, for example. In the DL, thecontroller/processor 675 provides header compression, ciphering, packetsegmentation and reordering, multiplexing between logical and transportchannels, and radio resource allocations to the UE 650 based on variouspriority metrics. The controller/processor 675 is also responsible forHARQ operations, retransmission of lost packets, and signaling to the UE650.

The TX processor 616 implements various signal processing functions forthe L1 layer (i.e., physical layer), for example. The signal processingfunctions includes coding and interleaving to facilitate forward errorcorrection (FEC) at the UE 650 and mapping to signal constellationsbased on various modulation schemes (e.g., binary phase-shift keying(BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying(M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded andmodulated symbols are then split into parallel streams. Each stream isthen mapped to an OFDM subcarrier, multiplexed with a reference signal(e.g., pilot) in the time and/or frequency domain, and then combinedtogether using an Inverse Fast Fourier Transform (IFFT) to produce aphysical channel carrying a time domain OFDM symbol stream. The OFDMstream is spatially precoded to produce multiple spatial streams.Channel estimates from a channel estimator 674 may be used to determinethe coding and modulation scheme, as well as for spatial processing. Thechannel estimate may be derived from a reference signal and/or channelcondition feedback transmitted by the UE 650. Each spatial stream isthen provided to a different antenna 620 via a separate transmitter618TX. Each transmitter 618TX modulates an RF carrier with a respectivespatial stream for transmission.

At the UE 650, each receiver 654RX receives a signal through itsrespective antenna 652. Each receiver 654RX recovers informationmodulated onto an RF carrier and provides the information to thereceiver (RX) processor 656. The RX processor 656 implements varioussignal processing functions of the L1 layer, for example. The RXprocessor 656 performs spatial processing on the information to recoverany spatial streams destined for the UE 650. If multiple spatial streamsare destined for the UE 650, they may be combined by the RX processor656 into a single OFDM symbol stream. The RX processor 656 then convertsthe OFDM symbol stream from the time-domain to the frequency domainusing a Fast Fourier Transform (FFT). The frequency domain signalcomprises a separate OFDM symbol stream for each subcarrier of the OFDMsignal. The symbols on each subcarrier, and the reference signal, isrecovered and demodulated by determining the most likely signalconstellation points transmitted by the eNB 610. These soft decisionsmay be based on channel estimates computed by the channel estimator 658.The soft decisions are then decoded and deinterleaved to recover thedata and control signals that were originally transmitted by the eNB 610on the physical channel. The data and control signals are then providedto the controller/processor 659.

The controller/processor 659 implements the L2 layer, for example. Thecontroller/processor 659 can be associated with a memory 660 that storesprogram codes and data. The memory 660 may be referred to as acomputer-readable medium. In the UL, the controller/processor 659provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the core network. The upper layerpackets are then provided to a data sink 662, which represents all theprotocol layers above the L2 layer. Various control signals may also beprovided to the data sink 662 for L3 processing. Thecontroller/processor 659 is also responsible for error detection usingan acknowledgement (ACK) and/or negative acknowledgement (NACK) protocolto support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets tothe controller/processor 659, for example. The data source 667represents all protocol layers above the L2 layer, for example. Similarto the functionality described in connection with the DL transmission bythe eNB 610, the controller/processor 659 implements the L2 layer forthe user plane and the control plane by providing header compression,ciphering, packet segmentation and reordering, and multiplexing betweenlogical and transport channels based on radio resource allocations bythe eNB 610, for example. The controller/processor 659 is alsoresponsible for HARQ operations, retransmission of lost packets, andsignaling to the eNB 610, for example.

Channel estimates derived by a channel estimator 658 from a referencesignal or feedback transmitted by the eNB 610 may be used by the TXprocessor 668 to select the appropriate coding and modulation schemes,and to facilitate spatial processing. The spatial streams generated bythe TX processor 668 are provided to different antenna 652 via separatetransmitters 654TX. Each transmitter 654TX modulates an RF carrier witha respective spatial stream for transmission.

The UL transmission is processed at the eNB 610 in a manner similar tothat described in connection with the receiver function at the UE 650.Each receiver 618RX receives a signal through its respective antenna620. Each receiver 618RX recovers information modulated onto an RFcarrier and provides the information to a RX processor 670. The RXprocessor 670 may implement the L1 layer, for example.

The controller/processor 675 implements the L2 layer, for example. Thecontroller/processor 675 can be associated with a memory 676 that storesprogram codes and data. The memory 676 may be referred to as acomputer-readable medium. In the UL, the control/processor 675 providesdemultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the UE 650. Upper layer packets fromthe controller/processor 675 may be provided to the core network. Thecontroller/processor 675 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations. Thecontrollers/processors 675, 659 may direct the operations at the eNB 610and the UE 650, respectively.

The controller/processor 675 and/or other processors, components and/ormodules at the eNB 610 or the controller/processor 659 and/or otherprocessors, components and/or modules at the UE 650 may perform ordirect operations, for example, operations 1100 in FIG. 11, and/or otherprocesses for the techniques described herein for assigning channels togroups of devices sharing bandwidth in presence of incumbent devices. Incertain aspects, one or more of any of the components shown in FIG. 6may be employed to perform example operations 1100, and/or otherprocesses for the techniques described herein. The memories 660 and 676may store data and program codes for the UE 650 and eNB 610respectively, accessible and executable by one or more other componentsof the UE 650 and the eNB 610.

Example Authorized Shared Access for 3.5 GHz

Due to the explosive growth in mobile broadband traffic and itsconcomitant strain on limited spectrum resources, the FederalCommunications Commission has adopted rules to allow commercial shareduse of 150 MHz of spectrum in the 3550-3700 MHz (3.5 GHz) band forlicensed and unlicensed use of the 3.5 GHz band for a wide variety ofservices.

Citizens Broadband Radio service (CBRS) is a tiered commercial radioservice in 3.5 GHz in the U.S. A Spectrum Access System (SAS) mayallocate channels within and across tiers, for example, according toaspects presented here (e.g., with reference to operations 1000illustrated in FIG. 10). These tiers can include, in order of priority,(1) incumbent licensees; (2) Priority Access licensees (PALs); and (3)General Authorized Access (GAA) operators.

Authorized shared access (ASA) allocates, to a secondary user(s),portions of spectrum that are not continuously used by an incumbentsystem(s). The incumbent system may be referred to as an incumbentlicensee, Tier 1 operator, primary licensee, or a primary user that isgiven a primary license for a band of frequencies. The incumbent systemmay not use the entire frequency band in all locations and/or at alltimes. The secondary user may be referred to as a secondary licensee ora secondary network. Aspects of the present disclosure are directed toan ASA implementation. Still, the ASA technology is not limited to theillustrated configurations as other configurations are alsocontemplated. The ASA spectrum refers to portion(s) of a spectrum thatis not used by a primary user and has been licensed for use by asecondary user, such as an ASA operator. ASA spectrum availability maybe specified by location, frequency, and/or time. It should be notedthat the authorized shared access may also be referred to as licensedshared access (LSA).

A PAL is an authorization to use a channel (e.g., an unpaired 10 MHzchannel) in the 3.5 GHz range in a geographic service area for a period(e.g., 3 years). The PAL geographic service area may be census tracts,which typically align with the borders of political boundaries such ascities or counties. PAL licensees can aggregate up to four PA channelsin any census tract at any given time, and may obtain licenses in anyavailable census tract. PALs may provide interference protection forTier 1 incumbent licensees and accept interference from them; however,PALs may be entitled to interference protection from GAA operators.

The third tier, GAA, permits access to bandwidth (e.g., 80 MHz) of the3.5 GHz band that is not assigned to a higher tier (i.e., incumbentlicensees or PALs). GAA may be licensed “by rule,” meaning that entitiesthat qualify to be FCC licensees may use FCC-authorizedtelecommunications equipment in the GAA band without having to obtain anindividual spectrum license. GAA operators may receive no interferenceprotection from PALs or Tier I operators, and may accept interferencefrom them.

In order to facilitate the complex CBRS spectrum sharing process, aSpectrum Access System (“SAS”), which may be a highly automatedfrequency coordinator, can be used to assign frequencies in the 3.5 GHzband, for example, according to aspects presented herein. The SAS canalso authorize and manage use of the CBRS spectrum, protect higher tieroperations from interference, and maximize frequency capacity for allCBRS operators.

Example ASA Architecture

In one configuration, as shown in FIG. 7, an ASA architecture 700includes an ASA controller 702 coupled to an incumbent networkcontroller 712 of a primary user and an ASA network manager 714 of anASA network. The primary user may be a primary ASA licensee and the ASAnetwork may be a secondary user.

In one configuration, the incumbent network controller is a networkentity operated by the primary user that controls and/or manages thenetwork operating in the ASA spectrum. Furthermore, the ASA networkmanager may be a network entity operated by the ASA network operatorthat controls and/or manages an associated network, including but notlimited to the devices operating in the ASA spectrum. Additionally, thesecondary licensee may be a wireless network operator that has obtainedan ASA license to use the ASA spectrum. Furthermore, in oneconfiguration, the ASA controller is a network entity that receivesinformation from the incumbent network controller on the available ASAspectrum that may be used by an ASA network. The ASA controller may alsotransmit control information to the ASA network manager to notify theASA network manager of the available ASA spectrum.

In the present configuration, the incumbent network controller 712 isaware of the use of the ASA spectrum by the primary user at specifiedtimes and/or locations. The incumbent network controller 712 may provideinformation to the ASA controller 702 for the incumbent usage of the ASAspectrum. There are several methods that the incumbent networkcontroller 712 can use to provide this information to the ASA controller702. In one configuration, the incumbent network controller 712 providesa set of exclusion zones and/or exclusion times to the ASA controller702. In another configuration, the incumbent network controller 712specifies a threshold for allowed interference at a set of locations.The threshold for allowed interference may be referred to as incumbentprotection information. In this configuration, the incumbent protectioninformation is transmitted to the ASA controller 702 over an ASA-1interface 716. Incumbent protection information may be stored by the ASAcontroller 702 in a database 706.

The ASA-1 interface refers to the interface between the primary user andthe ASA controller. The ASA-2 interface refers to the interface betweenthe ASA controller and the ASA network management system. Moreover, theASA-3 interface refers to the interface between the ASA network managerand the ASA network elements. Furthermore, geographic sharing refers toan ASA sharing model in which the ASA network can operate throughout ageographic region for an extended period of time. The network is notpermitted to operate in regions specified by exclusion zones.

The ASA controller 702 uses the information from the incumbent networkcontroller 712 to determine the ASA spectrum that may be used by the ASAnetwork. That is, the ASA controller 702 determines the ASA spectrumthat may be used for a specific time and/or a specific location based onrules specified in a rules database 708. The rules database 708 may beaccessed by an ASA processor 704 and stores the regulatory rules thatare set by local regulations. These rules may not be modified by theASA-1 or the ASA-2 interfaces, and may be updated by the individual ororganization that manages the ASA controller 702. The available ASAspectrum, as calculated by the rules in the rules database 708, may bestored in the ASA spectrum availability database 710.

The ASA controller 702 may send information to the ASA network manager714 on the available ASA spectrum via an ASA-2 interface 718, based onthe spectrum availability database. The ASA network manager 714 may knowor determine the geographic location of base stations under its controland also information about the transmission characteristics of thesebase stations, such as transmit power and/or supported frequencies ofoperation. The ASA network manager 714 may query the ASA controller 702to discover the available ASA spectrum in a given location or ageographic region. Also, the ASA controller 702 may notify the ASAnetwork manager 714 of any updates to the ASA spectrum availability inreal-time. This allows the ASA controller 702 to notify the ASA networkmanager 714 if the ASA spectrum is no longer available, so that the ASAnetwork can stop using that spectrum and the incumbent networkcontroller 712 can obtain exclusive access to the ASA spectrum in realtime.

The ASA network manager 714 may be embedded in a standard networkelement, depending on the core network technology. For example, if theASA network is a long term evolution (LTE) network, the ASA networkmanager can be embedded in an operations, administration, andmaintenance (OAM) server.

In FIG. 7, an incumbent network controller and a single ASA networkmanager are illustrated as being coupled to the ASA controller. It isalso possible for multiple ASA networks (e.g., ASA network A, ASAnetwork B and ASA network C) to be connected to an ASA controller 802,as in a system 800 shown in FIG. 8. ASA network A includes an ASAnetwork A manager 814 coupled to the ASA controller 802, ASA network Bincludes an ASA network B manager 820 coupled to the ASA controller 802,and ASA network C includes an ASA network C manager 822 coupled to theASA controller 802.

In this example, the multiple ASA networks may share the same ASAspectrum. The ASA spectrum may be shared via various implementations. Inone example, the ASA spectrum is shared for a given region, so that eachnetwork is restricted to a subband within the ASA spectrum. In anotherexample, the ASA networks share the ASA spectrum by using timingsynchronization and scheduling the channel access of the differentnetworks.

The system 800 may further include an incumbent network controller 812of a primary user communicating with the ASA controller 802 via an ASA-1interface 816, to provide incumbent protection information for adatabase 806. The ASA controller 802 may include a processor 804 coupledto a rules database 808 and ASA spectrum availability database 810. TheASA controller 802 may communicate with the ASA network managers 814,820 and 822 via an ASA-2 interface 818. The ASA networks A, B, C may besecondary users.

The ASA network manager(s) may interact with various network elements,such as eNodeBs, to achieve the desired spectrum use control. Theinteraction may be implemented via the ASA-3 interface between eNodeBsin the RAN and an ASA network manager node embedded in an operations,administration, and maintenance server. The RAN may be coupled to a corenetwork. An ASA controller may be coupled to the operations,administration, and maintenance server via an ASA-2 interface and to anetwork controller of a primary user via an ASA-1 interface.

In some cases, multiple incumbent network controllers are specified forthe same ASA spectrum. That is, a single incumbent network controllermay provide information about incumbent protection for a given ASAfrequency band. Therefore, the architecture may be limited to a singleincumbent network controller. However, it is noted that multipleincumbent network controllers may be supported. Still, it may bedesirable to limit the network to a single incumbent network controller.

Spectrum Sharing systems, such as SAS, allow for radio resources (e.g.,operating frequency, transmission power limits, and geographic areas) tobe assigned dynamically among multiple users and service providers whileproviding some degree of protection of other users/service providers andincumbent users that potentially have higher priority (e.g., fixedsatellite systems, WISPs, and government/military systems).

FIG. 9 illustrates an example architecture 900 of a spectrum sharingsystem. As illustrated, the spectrum sharing system may comprise one ormore Spectrum Access Servers (SASs) (e.g., an ASA Controller) which arethe entities that accept requests for radio resources from one or moreCitizens Broadband Radio Service Devices (CBSDs), resolve conflicts orover-constraints in those requests, and grant the use of resources toradio access services.

When competing users and radio systems, (e.g., CBSDs) vie for radioresources, there is also a challenge of protecting these radio resourcesfrom each other based on restrictions due to the radio accesstechnologies that are being used and a number of operational aspects forthose radio access technologies. For example, some users/systemoperators may be able to coexist in the same or neighboring radiochannels based on their use of the same (or compatible) radiotechnologies, compatible Self Organizing Network technologies,synchronized timing, common operational parameters (e.g., TDD slotstructures, common radio silence intervals, etc.), and access to thesame Core Networks for seamless mobility, etc. Accordingly, a SAS maydetermine channel assignments for different networks/system operatorsaccording to aspects presented herein.

Example Coverage Contour and Interference Thresholds Improvement For GAAChannel Assignment

As noted above, in a multi-tier commercial radio service (e.g., such ascitizens broadband radio service (CBRS)), different tiers of operatorsmay share portions of the same spectrum. In one reference example,different general authorized access (GAA) networks or technologies maybe able to share different portions of the same bandwidth. For example,in such a case, one GAA network may be allocated 10 MHz of spectrum andanother GAA network may be allocated 10 MHz of the same spectrum.

For GAA channel assignment among different networks in 3.5 GHz sharedspectrum, a Spectrum Access Servers (SASs)/coexistence manager (CXM) mayuse the following method. For example, the SAS/CXM may first create anetwork overlap graph, where two networks are connected if there is anoverlap in coverage between the two networks. The SAS/CXM may then colorthe graph with a minimum number of colors such that no two connectednetworks are assigned the same color. Each color represents a separatechannel and the color of each network represents the channel assigned tothe network.

In order to determine coverage overlap (e.g., which results in harmfulinterference) between two networks, the SAS/CXM may rely on coveragecontours and interference thresholds (X,Y) from one network to anothernetwork. For example, coverage contour of a network may be referred toas the union of contours around Citizens Broadband Radio Service Devices(CBSDs) of that network based on received signal level (e.g., X dBm)from each CBSD. For example, a coverage contour threshold may bedetermined by considering a CBSD as a transmitter and basing thecoverage contour threshold on the transmit power of the CBSD,propagation models, clutter, and indoor/outdoor information (e.g.building loss). A coverage contour may then be calculated around theCBSD where the received power from the CBSD is larger than the coveragecontour threshold, X.

Additionally, an interference threshold may be referred to as a maximumallowable aggregated interference (e.g., Y dBm) from one network at theboundary or inside the coverage contour of another network. For example,according to aspects, if the interference from an example Network A islarger than the interference threshold at any point at the boundary orinside the coverage contour of another example network B, then networksA and B may be said to have coverage overlap and are connected in thenetwork overlap graph. Aspects of the present disclosure presenttechniques for determining these thresholds so as to avoid negativeeffects associated with to aggressive or to conservative thresholdvalues, as described below.

FIG. 10 illustrates example operations 1000 for assigning channels to aplurality of entities in a wireless communications environment.According to certain aspects, example operations 1000 may be performed,for example, by a network entity such a SAS (e.g., one or more of theSASs illustrated in FIG. 9), co-existence manager (CXM), or anothernetwork entity operating between SAS and CBSD (e.g., EMS illustrated inFIG. 9 or ASA controller 702 or 802 illustrated in FIGS. 7 and 8,respectively). According to aspects, the SAS, CXM, or other networkentity may include one or more components (e.g., one or more processorsand/or memory) configured to perform operations described herein.

Operations 1000 begin at 1002 by determining a coverage contourthreshold and an interference threshold for each entity in the wirelesscommunications environment. At 1004, the SAS decides whether a firstentity and a second entity overlap in coverage based on the coveragecontour threshold and the interference threshold for the first entityand the second entity, wherein the first entity and the second entityoverlap if interference from the first entity is greater than theinterference threshold for the second entity at any point at a boundaryof or inside the coverage contour threshold of the second entity. At1006, the SAS selects a channel assignment for the first entity and thesecond entity based on the decision, wherein selecting a channelassignment for the first entity and the second entity comprisesassigning the first entity and the second entity orthogonal channels ifthe first entity and the second entity overlap in coverage. While notillustrated, operations 1000 may also include the SAS transmittinginformation to the first and second entity indicating the channelassignment.

As noted above, aspects of the present disclosure present techniques fordetermining coverage contour and interference thresholds so as to avoidnegative effects associated with to aggressive (e.g., small threshold)or to conservative (e.g., large thresholds) threshold values. Forexample, an aggressive choice of the coverage contour and interferencethresholds (X,Y) can result in ignoring some of the harmful interferencein channel assignment (e.g., in coloring the graph). For example, whenthe coverage contour and interference thresholds (X,Y) are set tooaggressively, a coexistence manager (CxM) may ignore some of thecoverage overlap between networks, which results in interference afterthe channel assignment is done (e.g. networks A and B have coverageoverlap, but CxM assigns them the same channel due to ignoring thecoverage overlap because of the bad choice of thresholds).Therefore,too-aggressive thresholds may result in coverage holes and poor UEperformance and increased interference.

A conservative choice of the coverage contour and interferencethresholds (X,Y), in some cases, may result in many unnecessaryconnections in the network overlap graph for which too many colors incoloring the graph are needed (e.g., too many orthogonal channels). Forexamples, when the coverage contour and interference thresholds (X,Y)are set too conservatively, the CxM may assume coverage overlap betweenall networks and tries to unnecessarily orthogonalize them, which mayresult in small bandwidth to each of these networks. Therefore,too-conservative thresholds may result in small channels (i.e., channelswith small bandwidth) for each network, resulting in poor networkthroughput and performance.

According to certain aspects, to resolve these issues and to determinecoverage contour and interference thresholds that reduce interferenceyet maintain an acceptable throughput, the network entity (e.g.,SAS/CXM/ASA) may first, in some cases, begin with a more conservativechoice of (X,Y). According to certain aspects, if this choice results intoo many colors (e.g., resulting in a bandwidth assigned to each network(e.g., color) below a bandwidth threshold), then the network entity mayadjust the thresholds to be more aggressive, for example, until thenumber and bandwidth of the channels becomes reasonable (e.g., in somecases, 10 MHz), for example, which may be a function of an interferencelevel, throughput, and of the particular type of technology of thenetwork (e.g., LTE, LTE-A, new radio (NR), LTE-TD, MultiFire (MF),LAA/eLAA, etc.). According to aspects, a in some cases goal of thenetwork entity may be to determine the coverage contour and interferencethresholds such that the channel assigned to each network is larger thanthe bandwidth threshold (e.g., 10 MHz).

According to certain aspects, the SAS/CXM may use radio frequency (RF)measurements to help determine the thresholds (X,Y) to maximizethroughput while reducing interference between networks. For example,the network entity may receive RF measurements from various CBSDs withinthe wireless communications environment. According to certain aspects,these RF measurements may include (but are not limited to) neighboringphysical cell IDs (PCIs) and neighboring E-UTRAN Cell Global Identifier(ECGIs), as well as reference signal received power (RSRP)/receivedsignal strength indicator (RSSI) measurements. Additionally, in somecases, these measurements can be network listen (NL) measurementsthrough CBSDs or UE measurements. That is the network entity may listenfor measurements taken by CBSDs or UEs within their respective networks,for example, to determine the RF distance and discover neighbors.

According to certain aspects, using these RF measurements, if a reportedreference signal received power (RSRP) of cell-edge UEs in a networkindicate a much larger/smaller coverage area than defined by thecoverage contour threshold considered at the network entity (i.e.,SAS/CXM), the thresholds can be adjusted by the network accordingly. Forexample, if the RSRP indicates a much larger coverage area than thecoverage contour threshold considered at the network entity, the networkentity may decrease the coverage contour threshold accordingly.According to aspects, decreasing the coverage contour threshold mayresult in increasing the area of contour, hence, providing protection tocell-edge UEs within the network. For example, if RSRP measurementsindicate that some UEs are at located far enough such that the receivedpower level of a base station of the network at a UE's location is −100dBm while coverage threshold (based on which the coverage contour isdefined) is −80 dBm (per 10 MHZ), the network entity may decrease thecoverage threshold since the actual coverage area is larger than whatthe network entity originally considered.

Additionally, if CBSDs experience large interference through ReceivedSignal Strength Indicator (RSSI) measurements, the network entity mayadjust the thresholds (e.g., decrease to make the thresholds moreconservative) accordingly to avoid harmful interference. Further, if astrong neighbor belonging to a different network is detected throughNL/UE measurements operating in the same channel, this may indicate thatthe choice of thresholds is too aggressive, and the thresholds may beadjusted by the network entity to be more conservative accordingly.

Additionally, in some cases, the coverage contour and interferencethresholds may be determined based on a tradeoff betweensignal-to-interference-plus-noise ratio (SINR) and throughput. Forexample, the network entity may receive SINR and throughput/bandwidthmeasurements from one or more devices (e.g., one or more UEs) in thewireless communications environment (e.g., CBSDs and/or UEs) and decidewhether to adjust the threshold or not based on the SINR and throughputmeasurements. For example, for SINR measurements, if the network entitydetermines that the UE-SINR distribution indicated the overallperformance/throughput in a network is “too good” (i.e., very littleinterference) it can make the threshold more aggressive to allow forlarger bandwidth.

According to certain aspects, based on the received SINR and throughputmeasurements, the network entity may determine the coverage contour andinterference thresholds according to BW*log(1+SINR), where BW is thebandwidth of a particular channel assigned to a CBSD and the SINR is theSINR for that particular channel. For example, using the equation notedabove, the network entity may determine a beneficial change in thecoverage contour and interference threshold. According to aspects, thenetwork entity may consider a change in the thresholds as beneficial ifthe combination of change in SINR and resulting change in number ofcolors used in the color graph is beneficial (e.g., interference isreduced and throughput is increased).

Additionally, in some cases, the coverage contour and interferencethresholds may be determined by the network entity as a function of CBSDdensity, for example, where CBSD density is based on GPS/locationinformation received by the network entity from one or more CBSDs. Forexample, if the network entity determines that for a particulargeographical location that there is a high density of CBSDs, the networkentity may adjust the coverage contour and interference thresholds to bemore conservative to reduce the interference observed between CBSDs.

According to certain aspects, due to some channel quantization impact,if the current number of colors results in unusable bandwidth, networkentity may adjust the coverage contour and interference thresholds (X,Y)(and, as a result, adjust the network overlap graph) until a minimumnumber of colors used in the color graph results in usable bandwidth(e.g., for a particular type of technology), as explained below.According to aspects, whether a particular bandwidth is usable ornon-usable may be based on predefined operating bandwidths of a network.

For example, assuming a total available GAA spectrum of 60 MHz and aminimum number of colors of 5 for current choice of (X,Y), the resultingchannel bandwidth would be 60/5=12 MHz, which may not be usable in anlong term evolution (LTE) system whose defined bandwidths are {1.4, 3,5, 10, 15, 20} MHz. Thus, in some cases, the network entity may adjustthe coverage contour and interference thresholds (X,Y) to be slightlymore aggressive such that minimum number of colors becomes 4, thusresulting in a usable LTE channel bandwidth of 60/4=15 MHz and therebyobtaining the benefit of a larger bandwidth (e.g., as compared to 12MHz). In other cases, the SAS/CXM may make the thresholds (X,Y) slightlymore conservative such that minimum number of colors becomes 6, thusresulting in a usable LTE channel bandwidth of 60/6=10 MHz and therebyobtaining the benefit of reduced interference (e.g., as compared to 12MHz).

According to certain aspects, the techniques presented above withrespect to determining coverage contour and interference thresholdbetween networks of a wireless communications environment may also beapplied to inter-technology channel assignment and inter-CBSD channelassignment (as opposed to inter-network channel assignment describedabove) to determine the coverage overlap between different technologiesor between different individual CBSDs (e.g., between LTE and WiMax orthe like).

According to certain aspects, the network entity may also adjust thecoverage contour and interference thresholds (X,Y) based on thepercentage of overlaps between individual CBSDs determined based oncoverage contour and interference thresholds (X,Y), and the area inwhich the overlap occurs between the individual CBSDs. For example, ifthere are many “small percentages of overlap” between CBSDs of twoexample networks, the network entity may adjust the coverage contour andinterference thresholds slightly more aggressive to disconnect some ofthe connections in the graph. According to aspects, this can result insmaller required colors (larger channels) while not substantiallyincreasing the interference.

FIG. 11 illustrates a communications device 1100 that may includevarious means-plus-function components configured to perform theoperations illustrated in FIG. 10. According to aspects, thecommunications device 1100 may comprise a network entity, such as a SAS,CXM, or ASA or may be configured to perform functions associated withsuch network entities.

As shown, the communications device 1100 includes means 1102 forperforming the operations illustrated at 1002 in FIG. 10. According toaspects, means 1102 may be configured to determine a coverage contourthreshold and an interference threshold for each entity of a pluralityof entities in the wireless communications environment.

Additionally, the communications device 1100 includes means 1104 forperforming the operations illustrated at 1004 in FIG. 10. According toaspects, means 1104 may be configured to decide whether a first entityand a second entity overlap in coverage based on the coverage contourthreshold and the interference threshold for the first entity and thesecond entity, wherein the first entity and the second entity overlap ifinterference from the first entity is greater than the interferencethreshold for the second entity at any point at a boundary of or insidethe coverage contour threshold of the second entity.

Further, the communications device 1100 includes means 1106 forperforming the operations illustrated at 1006 in FIG. 10. According toaspects, means 1106 may be configured to select a channel assignment forthe first entity and the second entity based on the decision, whereinselecting a channel assignment for the first entity and the secondentity comprises assigning the first entity and the second entityorthogonal channels if the first entity and the second entity overlap incoverage.

According to aspects, the means illustrated in FIG. 11 may compriseinclude various hardware and/or software/firmware component(s) and/ormodule(s), including, but not limited to a circuit, an applicationspecific integrated circuit (ASIC), or processor, configured to performthe operations illustrated in FIG. 10.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c, as well as any combination with multiples ofthe same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b,b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “identifying” encompasses a wide variety ofactions. For example, “identifying” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “identifying” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“identifying” may include resolving, selecting, choosing, establishingand the like.

In some cases, rather than actually communicating a frame, a device mayhave an interface to communicate a frame for transmission or reception.For example, a processor may output a frame, via a bus interface, to anRF front end for transmission. Similarly, rather than actually receivinga frame, a device may have an interface to obtain a frame received fromanother device. For example, a processor may obtain (or receive) aframe, via a bus interface, from an RF front end for transmission.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software/firmwarecomponent(s) and/or module(s), including, but not limited to a circuit,an application specific integrated circuit (ASIC), or processor, asdescribed above. Generally, where there are operations illustrated inFigures, those operations may be performed by any suitable correspondingcounterpart means-plus-function components.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or combinations thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, software/firmware, or combinations thereof. To clearlyillustrate this interchangeability of hardware and software/firmware,various illustrative components, blocks, modules, circuits, and stepshave been described above generally in terms of their functionality.Whether such functionality is implemented as hardware orsoftware/firmware depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the disclosure herein may be implemented or performedwith a general-purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in asoftware/firmware module executed by a processor, or in a combinationthereof. A software/firmware module may reside in RAM memory, flashmemory, ROM memory, EPROM memory, EEPROM memory, phase change memory,registers, hard disk, a removable disk, a CD-ROM, or any other form ofstorage medium known in the art. An exemplary storage medium is coupledto the processor such that the processor can read information from, andwrite information to, the storage medium. In the alternative, thestorage medium may be integral to the processor. The processor and thestorage medium may reside in an ASIC. The ASIC may reside in a userterminal. In the alternative, the processor and the storage medium mayreside as discrete components in a user terminal.

In one or more exemplary designs, the functions described may beimplemented in hardware, software/firmware, or combinations thereof. Ifimplemented in software/firmware, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by ageneral purpose or special purpose computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD/DVD or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code means in the form of instructions or datastructures and that can be accessed by a general-purpose orspecial-purpose computer, or a general-purpose or special-purposeprocessor. Also, any connection is properly termed a computer-readablemedium. For example, if the software/firmware is transmitted from awebsite, server, or other remote source using a coaxial cable, fiberoptic cable, twisted pair, digital subscriber line (DSL), or wirelesstechnologies such as infrared, radio, and microwave, then the coaxialcable, fiber optic cable, twisted pair, DSL, or wireless technologiessuch as infrared, radio, and microwave are included in the definition ofmedium. Disk and disc, as used herein, includes compact disc (CD), laserdisc, optical disc, digital versatile disc (DVD), floppy disk andBlu-ray disc where disks usually reproduce data magnetically, whilediscs reproduce data optically with lasers. Combinations of the aboveshould also be included within the scope of computer-readable media.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method of assigning channels in a wirelesscommunications environment, comprising: determining a coverage contourthreshold and an interference threshold for each entity of a pluralityof entities in the wireless communications environment; deciding whethera first entity and a second entity overlap in coverage based on thecoverage contour threshold and the interference threshold for the firstentity and the second entity, wherein the first entity and the secondentity overlap if interference from the first entity is greater than theinterference threshold for the second entity at any point at a boundaryof or inside the coverage contour threshold of the second entity; andselecting a channel assignment for the first entity and the secondentity based on the decision, wherein selecting a channel assignment forthe first entity and the second entity comprises assigning the firstentity and the second entity orthogonal channels if the first entity andthe second entity overlap in coverage.
 2. The method of claim 1,wherein: the first entity comprises a first network or a first citizensbroadband service device (CBSD); and the second entity comprises asecond network or a second citizens broadband service device (CBSD); 3.The method of claim 1, wherein determining the coverage contourthreshold and the interference threshold for each entity in the wirelesscommunications environment is based, at least in part, on a function ofsignal-to-interference-plus-noise ratio (SINR) and throughput.
 4. Themethod of claim 3, further comprising receiving SINR and throughputmeasurements from one or more devices in the wireless communicationsenvironment.
 5. The method of claim 3, wherein the coverage contourthreshold and an interference threshold for each entity is determinedaccording to:BW*log(1+SINR), where BW is the bandwidth of a particular channelassigned to a citizens broadband service device (CBSD).
 6. The method ofclaim 1, further comprising: receiving at least one or reference signalreceive power (RSRP) or received signal strength indicator (RSSI)measurements; and wherein determining the coverage contour threshold andthe interference threshold for each entity in the wirelesscommunications environment is based on at least one of the RSRP or RSSImeasurements.
 7. The method of claim 6, wherein: the first entitycomprises a first network and the second entity comprises a secondnetwork; and at least one of the RSRP or RSSI measurements are receivedvia a network listen procedure through a CBSD or through UE measurementsfrom a UE in the wireless communications environment.
 8. The method ofclaim 1, wherein: the first entity comprises a first network and thesecond entity comprises a second network; and the coverage contourthreshold and an interference threshold for each entity is a function ofcitizens broadband service device (CBSD) density based on locationinformation of CBSDs in at least one of the first network or the secondnetwork.
 9. The method of claim 1, further comprising transmittinginformation to the first entity and the second entity indicating thechannel assignment.
 10. The method of claim 1, further comprisingadjusting the coverage contour threshold and the interference thresholdfor each entity if current coverage contour threshold and theinterference threshold result in a bandwidth assigned to each entity isbelow a threshold.
 11. The method of claim 10, wherein updating thecoverage contour threshold and interference threshold comprises makingthe coverage contour threshold and the interference threshold moreaggressive.
 12. The method of claim 1, wherein the first entitycomprises a first network and the second entity comprises a secondnetwork; and further comprising: determining the coverage contourthreshold and the interference threshold resulting in a channelbandwidth to be assigned that is not useable by at least one of thefirst network or the second network; and adjusting the coverage contourthreshold and the interference threshold to be either more aggressive ormore conservative until a resulting channel bandwidth to be assigned isusable by at least one of the first network or the second network. 13.The method of claim 12, wherein a channel bandwidth is determined to beunusable based on predefined operating bandwidths for at least one ofthe first network or the second network.
 14. The method of claim 1,wherein the first entity comprises a first network and the second entitycomprises a second network; and further comprising: adjusting thecoverage contour threshold and the interference threshold based on apercentage of overlap between individual citizens broadband servicedevices (CBSDs) in at least one of the first network or the secondnetwork.
 15. An apparatus for assigning channels in a wirelesscommunications environment, comprising: at least one processorconfigured to: determine a coverage contour threshold and aninterference threshold for each entity of a plurality of entities in thewireless communications environment; decide whether a first entity and asecond entity overlap in coverage based on the coverage contourthreshold and the interference threshold for the first entity and thesecond entity, wherein the first entity and the second entity overlap ifinterference from the first entity is greater than the interferencethreshold for the second entity at any point at a boundary of or insidethe coverage contour threshold of the second entity; and select achannel assignment for the first entity and the second entity based onthe decision, wherein selecting a channel assignment for the firstentity and the second entity comprises assigning the first entity andthe second entity orthogonal channels if the first entity and the secondentity overlap in coverage; and a memory coupled with the at least oneprocessor.
 16. The apparatus of claim 15, wherein: the first entitycomprises a first network or a first citizens broadband service device(CBSD); and the second entity comprises a second network or a secondcitizens broadband service device (CBSD);
 17. The apparatus of claim 15,wherein the at least one processor is configured to determine thecoverage contour threshold and the interference threshold for eachentity in the wireless communications environment based, at least inpart, on a function of signal-to-interference-plus-noise ratio (SINR)and throughput.
 18. The apparatus of claim 16, wherein the at least oneprocessor is further configured to receive SINR and throughputmeasurements from one or more devices in the wireless communicationsenvironment.
 19. The apparatus of claim 18, wherein the at least oneprocessor is configured to determine the coverage contour threshold andan interference threshold for each entity according to:BW*log(1+SINR), where BW is the bandwidth of a particular channelassigned to a citizens broadband service device (CBSD).
 20. Theapparatus of claim 15, wherein the at least one processor is furtherconfigured to receive at least one or reference signal receive power(RSRP) or received signal strength indicator (RSSI) measurements; andwherein the at least one processor is further configured to determinethe coverage contour threshold and the interference threshold for eachentity in the wireless communications environment based on at least oneof the RSRP or RSSI measurements.
 21. The apparatus of claim 20,wherein: the first entity comprises a first network and the secondentity comprises a second network; and at least one of the RSRP or RSSImeasurements are received via a network listen procedure through a CBSDor through UE measurements from a UE in the wireless communicationsenvironment.
 22. The apparatus of claim 15, wherein: the first entitycomprises a first network and the second entity comprises a secondnetwork; and the coverage contour threshold and an interferencethreshold for each entity is a function of citizens broadband servicedevice (CBSD)density based on location information of CBSDs in at leastone of the first network or the second network.
 23. The apparatus ofclaim 15, wherein the at least one processor is further configured totransmit information to the first entity and the second entityindicating the channel assignment.
 24. The apparatus of claim 15,wherein the at least one processor is further configured to adjust thecoverage contour threshold and the interference threshold for eachentity if current coverage contour threshold and the interferencethreshold result in a bandwidth assigned to each entity is below athreshold.
 25. The apparatus of claim 24, wherein the at least oneprocessor is configured to adjust the coverage contour threshold and theinterference threshold by adjusting the coverage contour threshold andthe interference threshold to be more aggressive.
 26. The apparatus ofclaim 15, wherein: the first entity comprises a first network and thesecond entity comprises a second network; and the at least one processoris further configured to: determine the coverage contour threshold andthe interference threshold resulting in a channel bandwidth to beassigned that is not useable by at least one of the first network or thesecond network; and adjust the coverage contour threshold and theinterference threshold to be either more aggressive or more conservativeuntil a resulting channel bandwidth to be assigned is usable by at leastone of the first network or the second network.
 27. The apparatus ofclaim 26, wherein a channel bandwidth is determined to be unusable basedon predefined operating bandwidths for at least one of the first networkor the second network.
 28. The apparatus of claim 15, wherein: the firstentity comprises a first network and the second entity comprises asecond network; and wherein the at least one processor is furtherconfigured to: adjust the coverage contour threshold and theinterference threshold based on a percentage of overlap betweenindividual citizens broadband service devices (CBSDs) in at least one ofthe first network or the second network.
 29. An apparatus for assigningchannels in a wireless communications environment, comprising: means fordetermining a coverage contour threshold and an interference thresholdfor each entity of a plurality of entities in the wirelesscommunications environment; means for deciding whether a first entityand a second entity overlap in coverage based on the coverage contourthreshold and the interference threshold for the first entity and thesecond entity, wherein the first entity and the second entity overlap ifinterference from the first entity is greater than the interferencethreshold for the second entity at any point at a boundary of or insidethe coverage contour threshold of the second entity; and means forselecting a channel assignment for the first entity and the secondentity based on the decision, wherein selecting a channel assignment forthe first entity and the second entity comprises assigning the firstentity and the second entity orthogonal channels if the first entity andthe second entity overlap in coverage.
 30. A non-transitorycomputer-readable medium for assigning channels in a wirelesscommunications environment, comprising: instructions that, when executedby at least one processor, configure the at least one processor to:determine a coverage contour threshold and an interference threshold foreach entity of a plurality of entities in the wireless communicationsenvironment; decide whether a first entity and a second entity overlapin coverage based on the coverage contour threshold and the interferencethreshold for the first entity and the second entity, wherein the firstentity and the second entity overlap if interference from the firstentity is greater than the interference threshold for the second entityat any point at a boundary of or inside the coverage contour thresholdof the second entity; and select a channel assignment for the firstentity and the second entity based on the decision, wherein selecting achannel assignment for the first entity and the second entity comprisesassigning the first entity and the second entity orthogonal channels ifthe first entity and the second entity overlap in coverage.